• Journal of the Korean Society of Marine Environment & Safety
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• v.23 no.5
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• pp.595-602
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• 2017

In Korea, much research and development have occurred to enhance the technological competitiveness of tuna purse seining fisheries. Due to these efforts, fishing efficiency has been improved with the development of radar, sonar and global positioning systems for fish detection and revisions to the hull forms of tuna purse seiners. However, for skiff boats, net boats and speed boats, which are auxiliary working boats mounted on tuna purse seiners, technology has lagged behind relative to the modernization of the main vessel. In this study, the hull of an existing propeller-based net boat with steel wire net to protect tuna was changed to the hull of a water jet propulsion vehicle to reduce resistance and improve maneuverability. As a result, a prototype of a water jet propulsion option was produced according to the aluminum structure strength standards specified by the Ministry of Oceans and Fisheries, and safety was confirmed by performing a drop test. Moreover, through a sea trial test, an existing net boat was shown to have a speed of 12.0knots and a towing force of 2,545 kgf at 2,500 RPM. The prototype had a speed of 26.7 knots and a towing force of 2,011 kgf at 3,200 RPM, which satisfied the towing capacity standards of auxiliary working boats mounted on tuna purse seiners.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.2
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• pp.206-218
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• 2020

Located mostly inside the megacity of Busan, the Busan Southern Port is a multifunctional port with various nearby industry activities, including a joint fish market, ship repair facilities, and fishing boat facilities. If toxic chemicals generated by the industrial activities continue to flow into and accumulate in the sediment of the port, they can affect aquatic ecosystems and humans. Therefore, in this study, distribution levels and potential influent sources of organic pollutants, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and butyltin compounds (BTs), in the sediment were investigated. The sediment samples were collected from eight sampling sites in November 2013 (first phase) and November 2014 (second phase). The mean concentrations of PAHs, PCBs, and BTs in the first and second sampling phages were 4174.0 ng/g-dry wt. and 1919.0 ng/g-dry wt., 166.3 ng/g-dry wt. and 21 ng/g-dry wt., and 50.9 ng/g-dry wt. and 30.8 ng/g-dry wt., respectively. The concentrations of the organic pollutants detected in the seabed sediments were lower in the second phase than in the first phase. In this study, the inflow sources of PAHs, PCBs, and BTs were found to be combustion, land, and municipal sewage or industrial wastewater, respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.32 no.3
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• pp.252-255
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• 1999

The quality characteristics of the Korean traditional salt-fermented fish sauces, the traditional anchovy sauce (TAS) and the sandlance sauce(TKS) were evaluated comparing to the commercial anchovy sauce (CAS) and sandlance sauce (CKS). The acidity was higher in TKS than in TAS, whereas the contents of VBN, total-N and amino-N were higher levels in TAS. In color values, L and b values in TAS were generally higher than those in TKS, whereas a and ${\Delta}E$ values were higher in TKS. The contents of total free amino acids in TAS and TKS were $12.40\;g\%$ (w/v) and $9.549 g\%$ (w/v), respectively. The contents or six amino acids, alanine, glutamic acid, leucine, isoleucine, valine and Iysine were higher in TAS, whereas the contents of arginine, glutamic acid, leucine, alanine and valine were higher in TKS. Nucleotides such as IMP and hypoxanthine were principal components in both TAS and TKS. The nitrogen related compounds, TMAO, TMA and total creatinine were determined to be $108.8\;mg\%$ (w/v), $60.5\;mg\%$ (w/v), $62.4\;mg\%$ (w/v) in TAS, and those in TKS were $60.1\;mg\%$ (w/v), $24.1\;mg\%$ (w/v), $67.6\;mg\%$ (w/v), respectively.

• Fisheries and Aquatic Sciences
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• v.1 no.1
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• pp.82-93
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• 1998

Monthly changes of the gonad follicle index (GFI), reproductive cycle, egg-diameter composition, first sexual maturity of the Pacific oyster, Crassostrea gigas, were studied based on the samples which have been collected from the intertidal zone of Poryong west coast of Korea, from January to December, 1996. C. gigas, is dioecious, while a few individuals are alternatively hermaphroditic. Monthly variation of gonad follicle index (GFI) used for determination of spawning period, coincided with the reproductive cycle. GFI increased from April when seawater temperatures gradually increased and reached the maximum in May. And then, GFI sharply decreased from June to September due to spawning. Reproductive cycle of this species can be divided into five successive stages: in females, early active stage (March to April), late active stage (April to May), ripe stage (May to August), partially spawned stage (June to September) and spent/inactive stage (September to February); in males, early active stage (February to March), late active stage (April to May), ripe stage (May to September), partially spawned stage (June to September) and spent/ inactive stage (September to February). The diameter of fully mature eggs are approximately 50um. Spawning occurred from June to September, and two spawning peaks were observed in June and August when the seawater temperature was above $20^{\circ}C$. Percentages of the first sexual maturity of males of 20.1-25.0 mm in shell height were over $50\%$, while those of females of 25.1-30.0 mm in shell height were over $50\%$. All the males of > 30.1 mm and all the females of ^gt; 35.1 mm completed their first sexual maturity. The results suggest that C. gigas has a protandry phenomenon. Sex ratios of 919 oysters observed were 453 females $(49.29\%)$, 429 males $(46.68\%)$, 16 hermaphrodites $(1.74\%)$, and 21 indeterminate individuals $(2.29\%)$. In age class I, sex ratio of males were $64.00\%$, thus, a higher percentage than that of females. It was noted that $64.00\%$ of the young males (age class I) were more functional than females in age class I, but 2-3 year-old oysters showed higher percentage of females. Percentages of hemaphrodites in 2-3 year classes were relatively higher than those in other year classes. Histological pattern of hermaphrodites can be divided into two types: Type I (hermaphrodite having a number of newly formed developing oocytes on the oogenic tissues within a degenerating spermatogenic follicle after discharge of numerous spermatozoa) and Type II (hermaphrodite having two separate follicles in the same gonad).

• Korean Journal of Ichthyology
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• v.23 no.1
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• pp.61-69
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• 2011

Gene and promoter structures of metallothionein(MT) from Miho spine loach (Cobitis choii; Cypriniformes) were characterized, and the transcriptional responses to experimental exposures to heavy metals and heat stress were examined. The C. choii metallothionein displayed well-conserved features of teleostean metallothioneins at gDNA, mRNA and amino acid levels. Bioinformatic analysis predicted that the C. choii MT regulatory region potentially possessed various motifs or elements targeted by various transcription factors associated with metal-coordinating regulation (e.g., metal transcription factor-1), immune responses (e.g., nuclear factor kappa B), and thermal modulations (e.g., heat shock factor). Acute heavy-metal exposures to 0.5 or $1.0\;{\mu}M$ of cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni) or zinc (Zn) showed that MT transcription was significantly stimulated by Cd (9.6-fold relative to non-exposed control) and Cu (10.4-fold), only moderately by Mn (2.4-fold), but hardly by Ni and Zn. Elevation of water temperature from $25^{\circ}C$ to $31^{\circ}C$ caused a rapid modulation of MT mRNAs toward upregulation to 9.5-fold; however, afterward the elevated mRNA level slightly decreased during further incubation at $31^{\circ}C$ for 6 h. Results from this study suggest that MT-based expression assay could be a useful basis for better understanding the metal- and/or heat-caused stresses in this endangered fish species.

• Journal of Aquaculture
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• v.17 no.2
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• pp.115-121
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• 2004

In a series of feeding experiments using the newly established the first laboratory strain of a temperate photosynthetic ciliate, Mesodinium rubrum MR-MAL01, direct evidence was obtained for ingestion of the cultured M. rubrum cells by the bivalves like the Korean scallop, Chlamys farreri and Manila clam. Ruditapes phil-ippinarum. Each experimental Korean scallop and Manila clam removed up to 9,590 and 23,200 cells min-1, respectively. Small particles almost identical to the ruptured cells of MR-MAL01 culture were observed in the gut of the experimental bivalves, although no intact M. rubrum cell was found. In a 28 days rearing experiment, Isoshrysis galbana (KMCC H-2), a microalga, supported better growth of small Manila clam spat (0.46 mm in shell length) than MR-MAL01 strain. For the large Manila clam spat (0.84 mm in shell length), however. MR-MAL01 strain was a better prey item. Mass culture methods for this photosynthetic marine ciliate may be developed for use as live feed in aquaculture of the spat and broodstock of bivalve and small-mouthed fish larvae.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.4
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• pp.515-521
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• 2010

This paper dealt with the design and fabrication of an energy saving light emitting diode (LED) fishing lamp. Most fishes such as a squid, horse mackerel, mackerel, sardine and scabbard fish have characteristics for phototaxis and fishing lamps have promoted the fishery efficiency using their photo-reaction. In these days, metal halide lamp (MHL) as the fishing lamp, which consumes 1.5 kW and radiates harmful ultraviolet rays are mainly used. To develop the LED-fishing lamp, the penetration depth in sea water and the photo-reaction of a squid as light wavelength were studied. The experimental results showed the both characteristics were existed in blue color around 470 nm. Based on the results, we manufactured a 160 W and blue LED-fishing lamp which is consume about one-nine of 1.5 kW MHL. As energy saving effect, the use of LED-fishing lamp can reduce 128 kWh per an hour which is correspond to $CO_2$ of 86 kg for a 22ton-fishing boat equipped with 80-1.5 kW MHL. Now, the prototype LED fishing lampsare being evaluated on two fishing boats.

• Journal of Marine Bioscience and Biotechnology
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• v.2 no.1
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• pp.48-54
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• 2007

Bacillus polyfermenticus SCD (B. polyfermenticus SCD) has been appropriately used for the therapy of long-term intestinal disorders, because live strains in the form of active endospores can successfully reach the target intestine in humans. B. polyfermenticus SCD produces the most antibiotic-related materials. In the present study, B. polyfermenticus SCD was fermented with soybeans (BPFS) and its probiotic properties were investigated. B. polyfermenticus SCD and BPFS showed a broad spectrum of antimicrobial activity against pathogenic Gram-positive (Streptococcus parauberis, Streptococcus iniae, Lactococcus garviae) and Gram-negative (Flexibacter tractuosus, Vibrio harveyi, Vibrio vulnificus, Vibrio ordalii) bacteria and moulds (Aspergillus niger, Aspergillus oryzae). Sebastes schlegeli were used to examine survival rate and cleanup action by BPFS. Bacterial infection resulted in a mortality of up to 99% in the commercial fodder fed groups. BPFS both enhanced the growth rate of fry by improving their appetite and had cleaned by decreased eutrophication. Therefore, it seems appropriate that BPFS should be developed as an antibiotic replacement, favorable fodder additive, and antifungal material in fish farming systems.

• Korean Journal of Ichthyology
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• v.2 no.2
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• pp.159-168
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• 1990

Parental fish of R. uyekii(Mori) were colleted from the Nakdong River, Korea. Artificial insemination was carried out 4 times during June using the same pair (a female 52.70 mm TL and a male 56.80 mm TL). Unfertilized eggs are nearly spindly, opaque yellow in colour, measuring about 3.20-3.50 mm in length, about 1.50-1.80 mm in breadth. Hatching began about 50 hours after insemination at water temperature of $16.5{\sim}18.5^{\circ}C$. The newly hatched larvae are 4.10-4.50 mm in total length(TL), with 29-30 myomeres. Nine days after hatching, the larvae averaged 8.40 mm in total length and caudal notochord flexed at $45^{\circ}$. Eighteen days after hatching, total length reached 8.90 mm. The part of the fin-fold of the future dorsal and anal fins became high. Twenty-eight days after hatching, total length was 9.35 mm. The caudal fin-rays began to fork into two branches. The increased number of melanophores appeared newly on the head dorsal and anal fin-rays. The larvae reached the juvenile stage at 50-60 days after hatching and attained 14.50-16.20 mm in total length, and all fin-rays was formed.

• Korean Journal of Ichthyology
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• v.10 no.1
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• pp.115-127
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• 1998

The digestive tract of the rockfish, Sebastes schlegeli composed of pharynx, esophagus, stomach, intestine, anus and ten or eleven pyloric caeca. Pyloric caeca is blind sac of banana shape, and that is originated from pyloric portion of the stomach. The relative length of gut(RLG), that is length of digestive tract to standard length, is about 1.56(n=10). Esophageal muscularis consists of thin outer layer of longitudinal muscle and thick inner layer of circular muscle. Mucosal epithelium consists of columnar epithelium with short microvilli and contains numerous mucous secretory cell. The mucosal folds of the stomach are regular, and the muscularis consists of longitudinal, oblique and circular muscle layer. The chief cell of the gastric gland have a tubular mitochondria, endoplasmic reticula and numerous secretory granules in electron-dense. However, parietal cell contains small mitochondria, endoplasmic reticula and vacuoles in low electron density. Mucosal epithelium of the pyloric caeca and intestine composed of columnar epithelium, goblet cell, rodlet cell and dark cell. Columnar absorptive cell in the pyloric caeca and intestine contains well developed mitochondria, endoplasmic reticula, vesiculated granules in high electron density, pinocytotic vesicles and multivesicular body. Rodlet cell have a well developed cytoplasmic capsule and the endoplasmic reticula in the cytoplasm. Dark cell showing a high electron density in the cytoplasm and contains well developed mitochondria. Columnar epithelium of the intestine have a well developed intercellular junction and the microvilli which contains actin filament originated from the cytoplasm. Mucosal epithelium of the intestine have a longer microvilli and more abundant goblet cells than in the pyloric caeca.